Fuel injection valve

ABSTRACT

A fuel injection valve comprising a nozzle body having an inlet and an outlet and a cavity therebetween, a nozzle needle arranged in said cavity and spaced apart from said nozzle body to define an annular space therebetween for forming a fluid passage, said nozzle needle being mounted for reciprocating movement between opened and closed positions in said cavity, said nozzle body being sealed off at one end thereof by stop means, said nozzle needle at the end thereof adjacent said stop means being connected to a diaphragm arranged in said stop means, resilient guide means arranged in said nozzle body at the other end thereof from said stop means, said diaphragm and resilient guide means being mounted in said housing for securing said nozzle needle in a desired spatial relationship in said cavity whereby pressure applied onto said diaphragm acts to move said needle in said cavity between said open and closed position.

United States Patent Baumgart 1 June 6, 1972 54] FUEL INJECTION VALVE828,329 12 1951 Germany ..239/533 [72] Inventor: Walter Baumgm, Gergen,Germany 913,369 4/1954 Germany ..239/533 [73] Assignee: VebBarkas-Werke, Ifa-Kombinat fur P ima y EX min r-M- Hen n W Jr.

Kraftfahrzeugteile, Renak-Werke, Reichen- Assistant ExaminerEdwin D. Gant baeh, Germany Attorney-Nolte and Nolte [22] Filed: Sept. 17, 1970[57] ABSTRACT [21 1 Appl 72955 A fuel injection valve comprising anozzle body having an inlet and an outlet and a cavity therebetween, anozzle needle ar- 52 us. Cl ..239/533 ranged in Said cavity and Spacedapart from Said nozzle y [51] Int. Cl 1305]; 1/30 to define an annularspace therebetween for forming a fluid [58] Field of Search ..239/533 Pg Said nOZZle e l being mounted for reciprocating movement betweenopened and closed positions in said cavity, [56] Ref r n Cit d saidnozzle body being sealed off at one end thereof by stop means, saidnozzle needle at the end thereof adjacent said stop UNITED STATESPATENTS means being connected to a diaphragm arranged in said stop 7 470717 5/1949 Palumbo 239/533 means, resilient guide means arranged in saidnozzle body at 51 6 6/1956 Tavola /533 x the other end thereof from saidstop means, said diaphragm 2865675 12/1958 Roosa "'239/533 X andresilient guide means being mounted in said housing for 6 3/1970 Rere'"239/533 X securing said nozzle needle in a desired spatialrelationship in FOREIGN PATENTS OR APPLICATIONS l6l,356 4/1921GreatBritain ..239/533 797,797 5/1936 France ..239/533 said cavitywhereby pressure applied onto said diaphragm acts to move said needle insaid cavity between said open and closed position.

10 Claims, 1 Drawing Figure PATENTEDJUH 6 m2 0O V 0 6 j 7 ATTO RNEY FUELINJECTION VALVE This invention relates to an injection valve and moreparticularly relates to an injection valve for use in an internalcombustion engine.

The fuel injection valve of the type in accordance with the inventioncomprise a housing composed of a noule chamber and spring chamber sealedoff from one another. The nozzle chamber includes a fluid venting port,a nozzle needle which is spring biased to maintain the venting portnormally in closed position, upon reaching a predetermined excess ofpressure the needle is moved against the spring bias to position thefluid ort in open position and through the passage of fluid therethroughrelieving the pressure build-up within said nozzle chamber whereupon theneedle is returned to its position for closing off the venting port.

The known injection valves are provided with rigid needle guides andhave very little clearance between the nozzle body and the nozzleneedle. The nozzle needle serves in this type of construction as theclosing member. The sealing off of the nozzle chamber from the springchamber is effected in these known valves by resilient elements, inwhich connection the resilient members also serve as guides. Theresilient members are in the main constructed of a rubber material whichcan be either natural or synthetic and are generally secured in thedesired position by vulcanization techniques. The diaphragms areconstructed as discshaped members and can be made either from rubber ormetal. The diaphragms are arranged between the nozzle chamber and thespring chamber and are supported in part by specially molded and shapedparts, the diaphragms resting thereon and conforming in shape thereto,the aforesaid parts serving also to prevent penetration of the diaphragmby the nozzle needles.

Other constructions are known in which the sealing is brought about bymeans of alternately arranged rubber and metal discs. The diaphragm inthis type of construction is secured into position by the clampingaction of the various parts when screwed together.

The rigid needle guides are required to be prepared by extremely carefulmechanical procedures. Impurities in the fuel or slight deformations inthe nozzle body as for example arises in poor assembly or installationresult in a premature wearing out of the guide and therewith failure ofthe valve. The guides in addition exert a braking effect on the nozzleneedles because of the tight fit. If on the other hand greaterclearances are provided, losses due to oil leaks are unavoidable. Therapidly changing high pressures combined with the heat generated in useresult in a rapid wearing out of the diaphragms and in particular thediaphragms become porous at the points of contact thereof with theneedle and inevitably break or tear after some time. Oil losses andfailure of the device are the result.

In order to avoid the use of rigid needle guides, the known injectionnozzles have frequently been provided with specially constructed guidesand/or transmissions. These special constructions generally involve anincrease in the number of parts and particularly of the moving parts inthe valve and therewith also an increase in the dimensions of theinjection valve and the manufacturing costs. Furthermore, the errorfactor is likewise increased.

It is an object of this invention to provide a fuel injection valve freeof the disadvantages associated with the known constructions.

Another object of this invention is to provide an injection valve inwhich the essential parts and in particular the moving parts are kept toa minimum.

Still another object of the invention is to provide a valve in which thespring chamber and nozzle chamber are separated one from the other in anentirely leak proof manner.

Yet another object of the invention is to provide a fuel injection valvein which the needle is not unnecessarily loaded or damaged by the guidemeans.

These and other objects and advantages of the invention will appear fromthe following description which is accompanied by the drawing whichshows a vertical sectional view of a fuel injection valve embodying theprincipals of the invention.

In accordance with the invention a fuel injection valve is providedwhich is composed of a nozzle body having an inlet and an outlet forfluid and cavity therebetween, a nozzle needle is arranged in the cavityand spaced apart from the needle body so as to define an annular spacetherebetween which serves as a fluid passage, the nozzle needle ismounted in the cavity for reciprocating movement between open and closedpositions, the nozzle body is sealed off at one end thereof by a stopmeans, the nozzle needle at the end thereof adjacent said stop means isconnected to a diaphragm which is arranged in the stop means, resilientmeans are provided in the nozzle body at the end thereof opposite fromthe stop means, the diaphragm and resilient guide means being mounted inthe nozzle housing for securing the nozzle needle in a desired spatialrelationship in the nozzle cavity. Pressure applied onto the diaphragmin the aforesaid construction acts to move the nozzle needle between anopen and closed position.

In accordance with the invention the nozzle needle is arranged in thenozzle body in spaced apart relationship so .as to define an annularspace therebetween of comparatively great size. The annular space servesalso as the fuel conduit for the valve. At the bottommost end of thenozzle body there is arranged a packing assembly which includes apacking cone, the latter being dimensioned to ensure a tight fit betweenthe needle point and the injection orifice or opening. There is arrangedin the nozzle body above the packing assembly of resilient guide piecewhich is preferably made of a synthetic or plast material. To the otheror topmost end of the nozzle body, there is screwed a bushing having astop mounted therein. The uppermost end of the nozzle needle isincorporated into a membrane-like rubber of synthetic body hereinafterreferred to as a diaphragm. In order to increase the stability thereof,a metal insert is arranged in the diaphragm the same preferably beingsecured in place by vulcanization. By tightly screwing the bushing ontothe nozzle body, the stop is urged in the direction of the nozzle bodyand the diaphragm is thereby secured in a leak proof manner between thenozzle body and the stop and at the same time, the diaphragm iscentered. The stop is so constructed that all sides of the diaphragm canpress against it. A metal disc is secured to the diaphragm and servesfor absorbing the pressure exerted by the spring and to transmit thesame to the diaphragm. The spring force is directly transmitted to asupport which is inserted into an opening in the stop and which isdisposed on the metal plate. The bushing is sealed by a pressureadjusting screw which acts on a spring plate and by means of which theopening pressure of the valve can be adjusted. In order to protect theentire device, the upper end of the bushing is provided with a plasticcap.

The fuel injection valve works as follows:

When the force resulting from the pressure in the nozzle chamber of theconstruction of the invention corresponds to the force exerted by thespring, the needle begins to rise. The cross section of the packing conewhich is thereby exposed is thusly exposed to fuel pressure and thisforce acts on the needle in initiating its upward movement. The pressureacts also at the same time on the diaphragm urging it against the stopin the bushing. A pulling force is exerted on the needle which isvulcanized at its end portion to the interior of the diaphragm. Thediaphragm and the stop in the bushing are preferably so constructed thatfriction between these two parts in actual operation is very low. As theneedle is guided elastically only at its two ends, it can adjust itselfat any time automatically to the conical seat in the packing assembly.The friction between the needle and the guide members is very lowbecause the needle is provided with a sufficient degree of freedom ofmovement. The moving mass is reduced to a minimum. The same holds truefor the number of moving parts. The manufacture of the structuralcomponents involved requires no unusual expenditures. The production ofthe injection valve according to the invention can be carried out usingin the main commercially available parts. The failure of the injectionvalve due to jamming of the needle or by guides which have been damagedin operation is substantially eliminated. There are no losses due to oilleakage in that the noule chamber is completely sealed off in the nozzlebody.

The invention will be further described by reference to the drawing inwhich an embodiment of the invention has been shown.

A noule needle 8 is arranged in a nozzle body 1 so as to provide aconsiderable clearance space therebetween. At the bottommost end of thenozzle body 1, there is arranged a packing assembly 3 which is providedwith a packing cone 14 for the nozzle needle point and the injectionorifices. Above the packing assembly 3 in the noule body 1, there isarranged a resilient guide piece 9 preferably formed from a plastic orother synthetic material. At the other end of the nozzle body 1 there issecured by screwing a bushing 4 in which there is arranged a stop 6. Theupper end of the nozzle needle is vulcanized or compressed into amembrane like body preferably made of rubber or of a synthetic materialand which is referred to herein as a diaphragm 5. The stop 6 is soconstructed that all sides of the diaphragm can press onto the stop. inorder to increase the stability of the diaphragm a metal insert 7 isvulcanized into the diaphragm 5. When the bushing 4 is secured by thescrewing thereof onto the nozzle body, the stop 6 is urged in thedirection of nozzle body and the diaphragm 5 is sealed between thenozzle body 1 and the stop 6, and is centered at the same time. Thenozzle chamber in the nozzle body 1 is thus made completely leak proof.A metal disc 10 is arranged between the stop 6 and the diaphragm 5 andserves to absorb the pressure of the spring 11 and transmit it onto thediaphragm 5. The spring force is first absorbed by a support whichprotrudes through an opening in the stop 6 and is further transmittedtherefrom to the metal disc 9. At the top, the bushing 4 is terminatedby a pressure adjusting screw 12 which passes onto a spring plate 13 andby means of which the opening pressure of the valve can be regulated.For additional protection, the end of the bushing 4 which carries thepressure adjusting screw 12 is covered over with a plastic cap 16. Thefuel is introduced through the pressure inlet conduit 2 into the nozzlebody 1 and flows through the space established between the nozzle body 1and the nozzle needle 8. Due to the pressure built up in the nozzlechamber, the nozzle needle 8 is lifted from its seat in the packing cone14 and the injection process started up. The spring 11 acts tocounteract this venting or opening of the injection orifice and as soonas a pressure drop has taken place in the nozzle chamber by virtue ofthe jetting or venting of the fuel the nozzle needle 8 is urged back bythe spring 1 1 into the packing cone 14.

What is claimed is:

1. A fuel injection valve comprising a nozzle body having an inlet andan outlet and a cavity therebetween, a nozzle needle arranged in saidcavity and spaced apart from said nozzle body to define an annular spacetherebetween for forming a fluid passage, said nozzle needle beingmounted in said cavity for reciprocating movement between open andclosed positions, said noule body being sealed off at one end thereof bystop means, said noule needle at the end thereof adjacent said stopmeans being connected to a diaphragm arranged in said stop means,resilient guide means being arranged in said nozzle body at the otherend thereof from said stop means, said diaphragm and resilient guidemeans being mounted in said housing for securing said nozzle needle in adesired spatial relationship in said cavity, whereby pressure appliedonto said diaphragm causes said nozzle needle to move in said nozzlebody between said open and closed positions.

2. A fuel injection valve according to claim 1, said nonle needle beingconnected at its upper end to said diaphragm by vulcanization.

3. A fuel injection valve according to claim 1, said nozzle needle beingconnected at its upper end to said diaphragm by compression.

4. A fuel injection valve according to claim 1 wherein said diaphragm ismade of natural rubber, synthetic rubber or a plastic material. h

5. A fuel in ection valve according to claim 1 wherein said diaphragmand said stop means are constructed so as to conform to one another andto permit all of the external surfaces of the diaphragm to press uponthe abutting surfaces of said stop means.

6. A fuel injection valve according to claim 1 wherein said stop meanslimits the extension of said diaphragm.

7. A fuel injection valve according to claim 1 wherein said stop meansis mounted in a bushing.

8. A fuel injection valve according to claim 7 including a pressureregulating screw arranged at the top of said bushing for regulating theopening pressure of said valve.

9. A fuel injection valve according to claim 1 including spring meansarranged for urging said diaphragm in a downward direction.

10. A fuel injection valve according to claim 9 wherein a metal disc isarranged between said stop and said diaphragm, the force of said springbeing transmitted through said metal disc to said diaphragm.

1. A fuel injection valve comprising a nozzle body having an inlet andan outlet and a cavity therebetween, a nozzle needle arranged in saidcavity and spaced apart from said nozzle body to define an annular spacetherebetween for forming a fluid passage, said nozzle needle beingmounted in said cavity for reciprocating movement between open andclosed positions, said nozzle body being sealed off at one end thereofby stop means, said nozzle needle at the end thereof adjacent said stopmeans being connected to a diaphragm arranged in said stop means,resilient guide means being arranged in said nozzle body at the otherend thereof from said stop means, said diaphragm and resilient guidemeans being mounted in said housing for securing said nozzle needle in adesired spatial relationship in said cavity, whereby pressure appliedonto said diaphragm causes said nozzle needle to move in said nozzlebody between said open and closed positions.
 2. A fuel injection valveaccording to claim 1, said nozzle needle being connected at its upperend to said diaphragm by vulcanization.
 3. A fuel injection valveaccording to claim 1, said nozzle needle being connected at its upperend to said diaphragm by compression.
 4. A fuel injection valveaccording to claim 1 wherein said diaphragm is made of natural rubber,synthetic rubber or a plastic material.
 5. A fuel injection valveaccording to claim 1 wherein said diaphragm and said stop means areconstructed so as to conform to one another and to permit all of theexternal surfaces of the diaphragm to press upon the abutting surfacesof said stop means.
 6. A fuel injection valve according to claim 1wherein said stop means limits the extension of said diaphragm.
 7. Afuel injection valve according to claim 1 wherein said stop means ismounted in a bushing.
 8. A fuel injection valve according to claim 7including a pressure regulating screw arranged at the top of saidbushing for regulating the opening pressure of said valve.
 9. A fuelinjection valve according to claim 1 including spring means arranged forurging said diaphragm in a downward direction.
 10. A fuel injectionvalve according to claim 9 wherein a metal disc is arranged between saidstop and said diaphragm, the force of said spring being transmittedthrough said metal disc to said diaphragm.